Anorexia is not just all in the mind: Study finds sufferers might also struggle to gain weight because of their metabolism
- Scientists discovered eight genetic traits among patients with anorexia
- Mutations in DNA may mean anorexics process fat and sugar differently
- Some genes overlap with conditions including type 2 diabetes and OCD
- Others influence exercise levels, which may explain symptoms of over-activity
Anorexia is more than a mental disorder and has origins in a person’s genes which control their physical metabolism, too, research suggests.
A study has found people with the condition may have bodies less able to store fat as well as a higher chance of getting an obsessive mental illness.
Someone’s metabolism is a group of chemical reactions which helps the body use energy from food, and when it doesn’t work, a metabolic disorder may develop.
For example, type 2 diabetes develops when someone’s digestive system cannot properly absorb sugar – anorexia is now thought to have a similar physical base.
Anorexia has the highest mortality rate of any psychiatric illness because of the extreme weight loss it can cause.
And the researchers said identifying the true cause may explain why recovery rates have been so poor historically and help to boost them in the future.
Anorexia, characterised by extreme weight loss and under-eating, is more than a mental disorder and has origins in a person’s genetics, research suggests. Stock photo
The study, led by researchers at King’s College London and University of North Carolina at Chapel Hill, involved more than 100 academics worldwide.
They combined data collected by the Anorexia Nervosa Genetics Initiative and the Eating Disorders Working Group of the Psychiatric Genomics Consortium, initiatives which work to identify underlying biological that contributes to eating disorders.
The resulting dataset included 16,992 cases of anorexia nervosa and 55,525 controls, from 17 countries across North America, Europe, and Australasia.
Eight genetic variants linked to the life-threatening illness were discovered, some of which overlap with those seen in metabolic conditions like type 2 diabetes.
There were mutations in DNA’s instructions that control the body’s metabolism, particularly those involving blood sugar levels and body fat.
Some genetics linked to anorexia also influence exercise levels, which could explain why people with anorexia are so active.
The genetic basis of anorexia also overlaps with other psychiatric disorders such as obsessive-compulsive disorder, depression, anxiety, and schizophrenia.
All the findings were independent of genetic effects that influence body mass index (BMI).
WHAT IS ANOREXIA?
Anorexia is a serious mental illnesses where a person restricts their food intake, which often causes them to be severely underweight.
Many also exercise excessively.
Some sufferers may experience periods of bingeing, followed by purging.
Sufferers often have a distorted view of themselves and think they are larger than they really are.
Untreated, patients can suffer loss of muscle and bone strength, as well as depression, low libido and menstruation ceasing in women.
In severe cases, patients can experience heart problems and organ damage.
Behavioural signs of anorexia include people saying they have already eaten or will do later, as well as counting calories, missing meals, hiding food and eating slowly.
As well as weight loss, sufferers may experience insomnia, constipation, bloating, feeling cold, hair loss, and swelling of the hands, face and feet.
Treatment focuses on therapy and self-help groups to encourage healthy eating and coping mechanisms.
Source: Beat Eating Disorders
Anorexia may need to be thought of as a hybrid ‘metabo-psychiatric disorder’, scientists concluded in the journal Nature Genetics.
Previous research suggests that starvation or a period of dieting triggers biological changes in the body which disrupts the metabolism, therefore making it a condition rather than a mental illness which a patient can be treated for with therapy.
But alterations in the metabolism may be what cause the illness to arise initially, according to co-study author Dr Gerome Breen, from the National Institute for Health Research (NIHR) Maudsley Biomedical Research Centre and the Institute of Psychiatry, Psychology & Neuroscience.
He said: ‘Metabolic abnormalities seen in patients with anorexia nervosa are most often attributed to starvation.
‘But our study shows metabolic differences may also contribute to the development of the disorder.
‘Furthermore, our analyses indicate that the metabolic factors may play nearly or just as strong a role as purely psychiatric effects.’
Anorexia is a serious and potentially life-threatening illness, with symptoms including dangerously low body weight, an intense fear of gaining weight, and a distorted body image.
It affects between up to two per cent of women and 0.2-0.4 per cent of men, but experts believe the figure is much higher because the data is unclear.
Anorexia mainly effects young people during adolescence – but can last for decades.
Professor Janet Treasure, also from the Institute of Psychiatry, Psychology & Neuroscience, King’s College London, said: ‘Over time there has been uncertainty about the framing of anorexia nervosa because of the mixture of physical and psychiatric features.
‘Our results confirm this duality and suggest that integrating metabolic information may help clinicians to develop better ways to treat eating disorders.’
Corresponding author Professor Cynthia Bulik, of the University of North Carolina, said the genetic discovery could explain why recovery success is so poor.
Beat, one of the UK’s leading eating disorder charities, state that around 46 per cent of anorexia patients fully recover, but 20 per cent remain chronically ill.
She said: ‘A failure to consider the role of metabolism may have contributed to the poor track record among health professionals in treating this illness.
‘Our findings strongly encourage us to shine the torch on the role of metabolism to help understand why some individuals with anorexia nervosa drop back to dangerously low weights, even after hospital-based refeeding.
‘Until now, our focus has been on the psychological aspects of anorexia nervosa such as the patients’ drive for thinness.’
Genetic makeup has long been considered to play a role in the development of eating disorders.
Some research has found that female relatives of anorexia sufferers were 11.4 times more likely to suffer from anorexia compared to relatives of unaffected participants, according to Beat.
However, it is not understood what genetic traits are to blame and how these interact with environmental factors.
Andrew Radford, chief executive of eating disorder charity Beat, said: ‘This is ground-breaking research that significantly increases our understanding of the genetic origins of this serious illness.
‘We strongly encourage researchers to examine the results of this study and consider how it can contribute to the development of new treatments so we can end the pain and suffering of eating disorders.’
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